Telescopic mast

ABSTRACT

A telescopic mast comprising guidingly interfitted tubular elements which can be extended into a terminal position by means of a pressurized medium at which each extended tubular element lockingly engages with and is releasably retained by a holding mechanism provided at a tubular element such extended tubular element retained by such holder mechanism.

United States Patent [191 Frei [ June 25, 1974 1 TELESCOPIC MAST [75] Inventor: Ernst Frei, Regensdorf, Switzerland [73] Assignee: Conrad Kern AG, Regensdorf,

Switzerland 22 Filed: July 27,1972

2 1 App]. No.2 275,879

[30] Foreign Application Priority Data Aug. 13, 1971 Switzerland 11927/71 [52] US. Cl. 52/115, 52/118 [51] Int. Cl E04h 12/34, E04h 12/18 [58] Field of Search 182/146;52/1l5, 118,111; 287/58 TC; 248/407, 408

2,739,673 3/1956 Foster 52/111 2,983,342 5/1961 Howard 52/111 3,236,343 2/1966 Levy 49/7 3,267,625 8/1966 Holzschah 52/111 3,346,281 10/1967 Thompson 52/115 3,361,456 1/1968 Darand 52/111 3,398,645 8/1968 Nansel 52/115 Primary Examiner-Henry C. Sutherland Assistant ExaminerH. E. Raduazo Attorney, Agent, or Firm-Toren, McGeady and Stanger [57] ABSTRACT A telescopic mast comprising guidingly interfitted tubular elements which can be extended into a terminal position by means of a pressurized medium at which each extended tubular element lockingly engages with and is releasably retained by a holding mechanism provided at a tubular element such extended tubular element retained by such holder mechanism.

1 Claim, 6 Drawing Figures PATENIEH JUNE 5 I974 SHEET 2 0F 2 FIG. '4

FIG. 3

FIG. 5

1 TELESCOPIC MAST BACKGROUND OF THE INVENTION after frequently change their erection site, it is important that such telescopic masts can be easily erected and dismantled and transported without difficulty.

Constructions of telescopic masts having interfitting tubular elements which can be extended by means of a cable wound upon a winch or winding drum or the like and extending internally of the tubes are already known to the art. The withdrawal mechanism for extending the tubular elements requires a massive and cumbersome mast contruction, rendering more difficult the erection and dismantling of the mast and requiring a larger number of workers. The mechanism for withdrawing the tubular elements simultaneously serves the purpose of retaining the tubular elements in their extended position. However, such type withdrawal mechanisms are more prone to malfunction since the cable oftentimes binds and therefore there is hardly realized faultless functioning.

SUMMARY OF THE INVENTION Hence, it will be recognized from what has been discussed above, that this particular field of technology is still in need of constructions of telescopic masts which are not associated with the aforementioned drawbacks and limitations of the prior art proposals. Hence, it is a primary object of the present invention to provide a new and improved construction of telescopic mast which effectively and reliably fulfills the existing need in the art and overcomes the aforementioned drawbacks and limitations of the heretofore discussed proposals in the art.

Another and more specific object of the present invention relates to a new and improved construction of mast which can be quickly erected and dismantled in a troublefree manner, with a minimum amount of workers and a minimum need in material and which can also be easily transported.

A further significant object of the present invention relates to an improved construction of telescopic mast composed of interfitting tubular members which can be easily extended for erection purposes and similarly easily retracted for dismantling purposes and wherein the mast construction can be relatively simply and easily transported.

Now in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the aforementioned telescopic mast of this development is manifested by the features of guidingly interfitted tubular elements which can be extended into a terminal position by means of a pressurized medium. Each extended tubular element can be locked and releasably held in position by a holder mechanism provided at a tubular element located externally of such extended tubular element.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a schematic front view of a telescopic mast designed according to the teachings of the present invention in a retracted position of the tubular elements;

FIG. 2 ia a front view of the telescopic mast of FIG. 1 with the tubular elements in their extended position;

FIGS. 3 and 4 are respective fragmentary longitudinal sectional views through the telescopic mast construction of FIG. 2;

FIG. 5 is a cross-sectional view of the telescopic mast construction depicted in FIG. 3, taken substantially along the line A-A thereof; and

FIG. 6 is a cross-sectional view of the telescopic mast depicted in FIG. 3, taken substantially along the line BB thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, in FIG. 1 there are illustrated the interfitting tubular elements of a telescopic mast M with these elements in their retracted position. In this FIG. 1 the outermost stationary tubular element 1 is visible and such is supported at the ground through the agency of a base plate 2 and anchored by means of the spanning or bracing cables 3. These spanning cables or wires 3 are secured to a holder mechanism 4, the details of which will be discussed more fully hereinafter, and which holder mechanism 4 is arranged at the upper end of the tubular element 1. Within this first stationary tubular element 1, there are arranged a number of, in this case three, telescopically interfitting and extensible tubular elements 5, 6 and 7, wherein in such figure however only the ends thereof are visible. The tubular elements 5 and 6 are likewise provided at such ends with holder mechanisms.

Within the innermost tubular element 7 there is displaceably guided a withdrawal tube 8 equipped at its upper end with an indicator element, for instance a sighting mechanism 9 which indicates a certain height. This withdrawal tube 8 can be fixedly retained in its momentary withdrawn position by means of a fixing mechansim 13 (FIG. 2) mounted at the tubular element 8 and which has not been particularly shown in FIG. 1.

1 FIG. 2 illustrates the tubular elements 1, 5, 6 and 7 of the telescopic mast M in their extended position. The stationary tubular element 1, as already mentioned, is supported at the floor or ground by means of the base plate 2 and is anchored by means of the bracing or cables 3. The second tubular element 5 is engaged and fixedly retained by the holder mechanism 4 at the first tubular element 1, the third tubular element 6 is engaged and fixedly retained by the holder mechanism lfl'arranged at the second tubular element 5, and the fourth-tubular element 7 is engaged and fixedly retained by the holder mechanism 11 at the third tubular element 6. At the upper end of the fourth tubular element 7, there are secured the spanning or bracing cables 12 which together with the bracking cables 3 serve to anchor the mast.

Now internally of the fourth tubular element 7 there is displaceably guided the withdrawal tube 8 possessing the sighting mechanism 9. By means of the schematically illustrated fixing mechanism 13 which is arranged at the fourth tubular element 7, the withdrawal tube 8 can be fixedly retained in position in order to prevent any axial displacement thereof. The fixing mechanism 13 is, however, constructed in such a manner that the fixedly retained withdrawal tube 8 can be rotated upon overcoming a friction force by means of an aligning or adjusting lever 14. By downwardly tilting or otherwise suitably actuating the adjusting lever 14 it is possible to also secure the withdrawal tube 8 against rotation.

At the adjusting or aligning lever 14 there is secured a line or cable 15 which is connected in a manner still to be described with the holder mechanisms 4, l and 11 and which can be seized from the ground or floor.

FIGS. 3 and 4 illustrate longitudinal sectional views through the lower portion of the telescopic mast M depicted in FIG. 2. In this regard, there has been illustrated the first stationary tubular element 1 with its holder mechanism 4 and a portion of the second tubular element 5. The holder mechanisms and 1 1 are of the same construction as the holder mechanism 4 and guiding of the tubular elements 6 and 7 occurs in the same manner as the illustrated guiding of the tubular element 5 within the tubular element 1, so that it suffices to consider such aspects in conjunction with the components depicted in FIGS. 3 and 4.

Now as best seen by referring to FIGS. 3 and 5, the circular or round stationary first tubular element 1 is closed at its lower end by means of a closure plate 16 having an inlet valve 17 and a discharge or outlet valve 18. Furthermore, at such closure plate 16 there are welded two parallel flanges 19 which are disposed perpendicular to the closure plate 16, and each of which flanges l9 possesses a respective opening. A respective bolt member 20 is rotatably inserted through each such opening and these bolt members are supported at two support plates 21 secured to the base plate 2. The bolts 20 form the pivot axis for the first tubular element 1. Two holes 22 are machined at the base plate 2, these holes 22 serving to receive suitable attachment elements for anchoring the base plate 2.

As best seen by referring to FIGS. 3, 4 and 6, at the upper end of the tubular element 1, there are secured three guide elements 23, 24 and 25 which are arranged offset by 120 with respect to one another. Each of these guide elements 23, 24 and 25 possesses an axially parallel plate-shaped arm 26 which is connected with the tubular element l, and at the upper end of which there is mounted the associated hollow cylindrical threaded bushing or sleeve 27, in which there is threaded a respective screw 28, preferably formed of plastic. These screws 28 serve on the one hand as guides for the tubular element 5 and on the other hand as stop or impact means against which abuts a ring flange 29 mounted at the tubular element 5, so that there is realized a limitation in the axial movement of the tubular element 5 in upward direction. The bracing cables 3 are secured to the arms 26.

Continuing, at the arm 26 of the guide element 23, there is rotatably secured a deflectable stop means for instance in the form of a pawl 30 or equivalent consisting of two parallel plates 3011 which receive therebetween the associated arm 26. The bolt 31 forming the axis of rotation of the pawl 30 is not arranged at the center of gravity of such pawl or latch 30, rather offset with respect thereto, as shown in FIGS. 3 and 4, so that the pawl 30 under the action of gravitational force, and as particularly well shown in FIG. 4, drops downwards by means of its end 30c facing away from the tubular element 5. Both of the plates 30b of the pawl 30 are interconnected by means of a connection element 32 which extends parallel to the bolt 31. This connection element 32 will be understood to protrude at both ends past the plates 30a and as best seen by referring to FIG. 3 serves for securing a ring element 33 defining a removable clamping element and formed of a plastic material, for instance rubber. This ring element 33 extends from one end of the connection element 32 behind and past the arm 26 to the other end of the connection element. Ring element 33 prevents any tilting of the pawl or latch 30 and retains such in its locking or racheting position in which the ring flange 29 defining a cam element and mounted at the tubular element 5 comes to bear against the pawl 30, so that the tubular element 5 is fixedly retained in its desired terminal position. In the locked position the connection element 32 bears against the arm 26 and prevents the pawl 30 from being pushed into the tubular element 5.

The line or cable 15 previously considered already with regard to FIG. 2, and which is secured to the adjusting or alignment lever 14, connects the ring element 33 provided at the holder mechanism 4 as well as the ring elements 33 analogously provided at the holder mechanisms 10 and I1 and serves the purpose of pulling down or removing such ring elements 33 in the finished mounted position of the mast. At the lower end of the second tubular element 5 there are mounted three metallic rings 34 with intermediate spaces, wherein there are embedded in such intermediate spaces sealing elements 35 in the form of sealing 0- rings.

The metallic rings 34 and the sealing elements 35 serve to guide the tubular element 5 within the tubular element 1 and also as seals for the pressurized medium serving to extend the mast M and together with the circular-ring. shaped cross-sectional surface 5a of the tubular element 5 as a piston surface.

Beneath the ring or ring flange 29 there are secured to the tubular element 5 analogous metallic rings 36 and a sealing ring 37 which carry out guiding and sealing functions. In contrast to the tubular elements 5 and 6 which internally form a throughpassage channel for the pressurized medium, the tubular element 7 mounted as the last telescopically extensible tubular element is appropriately closed at its lower end in order to prevent further throughpassage of such pressurized medium.

During mounting of the telescopic mast, the base plate 2 is initially anchored to the ground or floor and the first tubular element 1 into which there are inserted all the remaining tubular elements 5, 6 and 7 and the withdrawal tube 8, is secured by means of the bolts 20 to the base plate 2, whereby the assembly or unit with the tubular elements is tilted over and laid down at the ground or floor. In this tilted position the withdrawal tube 8 is withdrawn to such an extent as is necessary for the desired height of the sighting mechanism 9 above the ground and thereafter is locked in place by means of the fixing mechanism 13. Then all of the pawls 30 are provided with a ring element 33 clamped about the arm 26, which ring element holds the locking pawl in its locked or racheted position. The thus mounted ring elements 33 are connected with one another by means of the cable which is secured at one end to the adjusting or alignment lever 14.

Thereafter, the tubular unit or package is collectively erected and by means of the bracing or spanning cables 3 mounted at the guide elements 23, 24, 25 of the first tubular element 1 clamped in a vertical position. Then there is connected to the inlet valve 17 a source of pressurized medium, such as air for instance. A foot pump can be employed by way of example as a suitable source of such compressed air. The pressurized medium which is pumped into the interior of the tubular element 1 fills the inner compartment formed by the tubular elements 1, 5 and 6 and begins to act upon the metallic rings 34 serving as piston surfaces and the cross-sectional surface of the extensible tubular elements 5, 6 and 7. As a result, the tubes 5, 6 and 7 are upwardly displaced in a random sequence. At the region of their terminal position, the tubular elements 5, 6 and 7 travel by means of their ring flanges 29 upon the contact surfaces 30a of the pawls retained in their locked position by the ring element 33, so that the pawls 30 are pushed or tilted back and traveled over by the ring flanges 29. After passage of the ring flanges 29, the pawls 30 are again placed back into their locked or racheting position by means of the elastic ring element As soon as the ring flanges 29 impact against the movement limiting screws 28, then the tubular elements have reached their uppermost position. By slightly reducing the pressure of the pressurized medium, the tubular elements 5, 6 and 7 are lowered to such an extent until they bear by means of their n'ng flanges 29 upon the associated pawl 30 and thus are fixedly held in their position. Contact of the ring flange 29 upon the pawl 30 brings about a locking action against rotation of the relevant tubular section (FIG. 3). Now after shutting-off the inlet valve 17 the source of pressurized medium can be removed.

After clamping the bracing or spanning cables 12, the ring elements 33 are torn away by pulling upon the line or cable 15, so that the pawls 30 no longer can unlock owing to the weight of the tubular elements bearing thereagainst.

By means of the cable 15 secured to the alignment lever 14 the withdrawal tube 8 with the sighting mechanism 9 is now rotated into its proper position and by flipping over this alignment lever 14 downwards is locked in this position.

During disassembly of the mast, and by means of the source of pressurized medium which is again connected with the arrangement, the pressure internally of the tubular elements is increased and the tubular elements 5, 6 and 7 are raised to such an extent until they abut with their ring flanges 29 against the screws 28. Now since the weight of the tubular elements no longer bears upon the pawls 30 and such are no longer held by ring elements 33 in their locked position, the pawls 30 rotate about the bolts 31 into their unlocked position (FIG. 4) in which they release the tubular elements.

Upon opening the discharge valve 18 the pressurized medium is vented and the tubular elements 5, 6 and 7 lower until they are completely retracted.

After loosening the spanning cables 3 and laying over the tubular element 1, it is possible to again insert the withdrawal tube 8 similar to the situation when mount- The extensible length of the telescopic mast can be changed in that in certain cases predetermined tubular elements are not extended. This can be realized by appropriately coupling the ends of two or more tubular elements in their retracted position.

The elastic rubber element 33 which retains the associated pawl or latch 30 in its racheted or locked position, must, as described, be removed prior to dismantling of the mast, in order to permit retraction of the tubular element. Instead of using a rubber ring which, as already described, can be torn away, it is also conceivable to use a ring element which consists partially or entirely of an elastic material, which after a brief time under the influence of weather effects disintegrates or decomposes, so that the ring element is destructed.

it is also possible to employ as a ring element which essentially consists of a non-decomposing elastic mate rial, a partial member of a decomposing material which however need not be elastic.

Further possibilities reside in the fact that the ring element formed of a non-decomposing material is subdivided and at the separation location is adhesively bonded together again by means of an adhesive. The adhesive in such case then must lose its bonding properties under the effects of weather, yet should retain the ring element together such that it does not already fall apart during mounting.

The described mast can be effortlessly erected by two men and also again dismantled. Since the tubular elements are fixedly retained in their extended terminal position by the mechanical holder mechanisms, the pressurized medium must only serve for extending the tubular elements. Not as great sealing requirements need be placed upon the seals between the individual movable tubular elements as would be the case if the pressurized medium also were employed for fixedly retaining the tubular elements in their desired terminal position.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. Accordingly,

What is claimed is:

l. A telescopic mast assembly comprising, in combination, a plurality of tubular members mounted together to be telescopically movable relative to each other, said members being slidably interfitted in fluid tight engagement to enable said mast to be telescopically extended by introduction therein of a pressurized fluid medium, means for controllably introducing and exhausting said fluid medium from within said mast assembly, and latching means for releasably holding said mast in a telescopically extended position for permitting retraction of said mast by first introducing therein and subsequently exhausting therefrom said fluid medium, said latching means including an abutment memberv affixed to each of said tubular members, a latch member pivotally mounted to each of said tubular members at a location to operatively engage the abutment memberaffixed to an adjacent tubular member and a resilient clamping element removably engaging said latch member to hold said latch member in a first pivotal position to engage said abutment member, thereby to prevent relative movement of adjacent tubular members in the direction of telescopic retraction of said mast assembly, said latch member being eccentrically pivotally mounted at a point permitting said latch member to freely pivot by its own weight to a second pivotal position at which it will not be engaged by said abutment member, thereby to permit retracting movement of said tubular members, said latch member being configured to permit passage thereby without engagement of said abutment member in the direction of telescopic extension of said mast when said latch member is held in said first pivotal position by said clamping element, said removal of said clamping element operating to permit said latch member to pivot by its own weight to said second pivotal position, said mast assembly being telescopically extendable by introduction therein of said fluid medium to move said abutment member past said latching member while said latching member is held in said first pivotal position by said clamping element, with exhausting of said fluid medium thereafter operating to cause engagement of said abutment member by said latching member to prevent retracting movement of said tubular members, said mast assembly being thereafter telescopically retractable by first removing said clamping element from said latching member and thereafter extending said mast assembly slightly by further introduction therein of said fluid medium to enable pivoting by its own weight of said latching member to said second pivotal position whereby subsequent exhausting of said fluid medium from said mast assembly will operate to effect full retraction thereof, and said resilient clamping element is formed along a portion thereof with a severable joint forming a tear line along which said element may be destructably removed from engagement with said latch member. 

1. A telescopic mast assembly comprising, in combination, a plurality of tubular members mounted together to be telescopically movable relative to each other, said members being slidably interfitted in fluid tight engagement to enable said mast to be telescopically extended by introduction therein of a pressurized fluid medium, means for controllably introducing and exhausting said fluid medium from within said mast assembly, and latching means for releasably holding said mast in a telescopically extended position for permitting retraction of said mast by first introducing therein and subsequently exhausting therefrom said fluid medium, said latching means including an abutment member affixed to each of said tubular members, a latch member pivotally mounted to each of said tubular members at a location to operatively engage the abutment member affixed to an adjacent tubular member and a resilient clamping element removably engaging said latch member to hold said latch member in a first pivotal position to engage said abutment member, thereby to prevent relative movement of adjacent tubular members in the direction of telescopic retraction of said mast assembly, said latch member being eccentrically pivotally mounted at a point permitting said latch member to freely pivot by its own weight to a second pivotal position at which it will not be engaged by said abutment member, thereby to permit retracting movement of said tubular members, said latch member being configured to permit passage thereby without engagement of said abutment member in the direction of telescopic extension of said mast when said latch member is held in said first pivotal position by said clamping element, said removal of said clamping element operating to permit said latch member to pivot by its own weight to said second pivotal position, said mast assembly being telescopically extendable by introduction therein of said fluid medium to move said abutment member past said latching member while said latching member is held in said first pivotal position by said clamping element, with exhausting of said fluid medium thereafter operating to cause engagement of said abutment member by said latching member to prevent retracting movement of said tubular members, said mast assembly being thereafter telescopically retractable by first removing said clamping element from said latching member and thereafter extending said mast assembly slightly by further introduction therein of said fluid medium to enable pivoting by its own weight of said latching member to said second pivotal position whereby subsequent exhausting of said fluid medium from said mast assembly will operate to effect full retraction thereof, and said resilient clamping element is formed along a portion thereof with a severable joint forming a tear line along which said element may be destructably removed from engagement with said latch member. 